title: Evaluating Laguerre-Gaussian beams with an invariant parameter.
abstract: We define a new parameter for Laguerre-Gaussian (LG) beams, named Q(p,l), which is only related to mode indices p and l. This parameter is able to distinguish and evaluate LG beams. The Q(p,l) values are first calculated theoretically and then measured experimentally for several different LG beams. Another mode quality parameter, M(2) values, are also measured. The comparison between Q(p,l) and M(2) shows the same trend for the quality of the LG mode, while the measurement of Q(p,l) is much easier than M(2).
authors.forename: Junling
authors.initials: J
authors.lastname: Long
authors.forename: Ruifeng
authors.initials: R
authors.lastname: Liu
authors.forename: Feiran
authors.initials: F
authors.lastname: Wang
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Wang
authors.forename: Pei
authors.initials: P
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Gao
authors.forename: Fuli
authors.initials: F
authors.lastname: Li